This invention relates to an apparatus and method for processing aqueous wastes containing fats, oils, and relatively large proportions of inorganic and organic solids: in particular, the invention relates to an apparatus and method for processing the waste which collects in traps such as restaurant traps. The purpose of this apparatus and process is to separate and treat the solids portion of these trap wastes so that they are acceptable for ordinary landfill disposal, to render the remainder of the trap wastes treatable in a typical sewage treatment plant.
Many institutions generate wastes which contains a high percentage (often as much as 50% or more) of mixed organic and inorganic solids as well as water, fats and oils, etc. One example of such wastes is that which collects in restaurant sink traps. This "trap waste" is periodically removed from such traps by pumping the semi-liquid waste into portable tanks or the like typically contains 40% to 60% or more of mixed inorganic and organic solids such as bones, paper, plastics, garbage, and the like, with the remainder constituting various amounts and types of fats, oils, grease, surfactants (soaps), and aqueous components. Such trap wastes or "trap pumpings" are typically relatively intractable and resistant to treatment in sewage treatment plants due in large part to the high proportion of solids present and the wide variety of substances found in such wastes. Until recently, the trap waste removed from, for example, restaurant traps was either disposed of by dumping or landfilling the trap waste, possibly after the removal of some of the aqueous components of the trap waste, or by drying and incinerating or burning the trap waste.
With increased interest in the environment and increased regulatory requirements for pollution abatement equipment, such methods of trap waste disposal are no longer practicable. Dumping or landfilling of trap waste is undesirable due to the potentially harmful environmental consequences, the continually increasing high cost of landfilling, and the increasingly limited locations in which such disposal is permitted. Burning of dewatered trap waste is possible, but, because of the very high incinerator temperatures that are required to completely combust the plastics typically found in trap waste, burning of large quantities of trap waste in a way that will meet regulatory requirements is generally infeasible. Further, incineration affects only part of the solids typically present in trap wastes.